- A reference point for anyone who understands physics, but finds it hard to visualise speed in metres per second. the scale is assumed to be 1 pixel to a centimetre, thus the boy is fairly tall, 180cm in his current posture, and the raft is about 150cm. The river is also 70cm deep, and the two clouds are 190m apart. done after reading about the rate of flow of water in the river that may have existed in Gale crater, Mars, where the MSL, Curiosity, is studying rocks.
